Power transmission mechanism for operating brakes



Aug 16, 1938. H. E. HODGSON 2,127,335

POWER TRANSHI S S I ON MECHAN I SM FOR OPERATING BRAKES Filed Oct. 2, 1936 I ll\\\\\\\\\\\\ QQ WWW" 59 @ZE 59 MNWMAW N l I WNW/1% Patented Aug. 16,

PATENT OFFICE rowan TRANSMISSION MECHANISM son OPERATING mourns Howard E. Hodgson, Wauwatosa, Wia, assignor to Cutler-Hammer, Inc., Milwaukee, Wla, a

corporation of Delaware Application October 2,

I 5 Claims.

This invention relates to improvements in power transmission mechanisms, and while not limited thereto is particularly applicable to speed reducing driving mechanisms for motor operated brakes.

The invention has among its objects to provide an improved speed reducing driving mechanism for use in connection with motor driven apparatus such as motor operated brakes which is exceedingly compact and rugged in construction and reliable and eiiicient in operation.

Another object is to provide a speed reducing mechanism for apparatus of the aforesaid character which is completely enclosed and self-lubricating.

Another object is to provide a speed reducing mechanism for apparatus of the aforesaid character having means associated therewith for positively stopping the same in opposite limits and for frictionally dissipating the kinetic energy present in the driving motor in such limits.

Various other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates an embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of modification without Figs. 4 and 5 are sectional views on lines 4-4 and 5--5 of Fig. 2, and Fig. 6 is a sectional View on line 6-6 of Fig. 3. Referring to Fig. 1, the driving mechanism is shown in connection with a brake including a,

brake drum I to be secured to a motor or other device to be "braked, oppositely arranged .brake shoes 2 and 3 for frictionally engaging said drum on opposite sides thereof, and levers 4 and 5 supporting said shoes, respectively. The lower ends of levers 4 and 5 are pivotally mounted upon pins 6 and 1, respectively, carried by a stationary supporting base 8 and the upper end of lever 5 has a pivot pin 9 mounted thereon which carries an operating lever Ill. Said operating lever is pro- 1936,. Serial No. 103,707 (Cl. 188171) vided with arms ii and i2, the latter being pivotally connected to one end of alink I3 by a pin 14. The opposite end of link l3 extends through an opening in the upper end of lever 4 and is provided with an adjustable nut l5 for engaging a curved surface IS on said lever. Stop nut I5 is held in engagement with the surface It by a coil spring l1 which is held under compression between lever 4 and a nut i8 on link l3.

'-Arm II has a spring 19 associated therewith which is held under compression between a lug 20. on lever 5 and a washer 2i fixed to the lower end of a pin 22. Arm II and lug 20 are each provided with an opening for receiving pin 22 and the upper end of said pin is provided with an adjustable nut 23 for engaging said am on the upper side thereof. medium of lever l0 and link l3 to bias levers 4 and 5 toward each other for engagement of brake shoes 2 and 3 with brake drum I. Upon upward movement of arm i I out of the position shown in Fig. 1 arm l2 and link i3 act as a toggle to Spring l9 acts through the move levers 4 and 5 in opposite directions for release of the brake shoes 2 and 3 from drum I.

The brake is provided with a vertically arranged operatingmotor 25 which is fixed to a side extension on base 8. Said operating motor is operatively connected to the free end of arm ii through the medium of a speed reducing jack 26 including a rotatable sleeve nut 21 having a slip clutch driving connection 28 between the same and motor 25, and a non-rotatable screw 29 which is operatively connected to the free end of arm Ii.

The sleeve nut 21 has -a bored portion "30 of reduced diameter intermediate its ends and the screw 29 is slidable therein and is provided with an upwardly extending cylindrical shank 3| which is of reduced diameter. The portion 30 of sleeve nut 21 has a half round spiral groove 32 therein and screw 29 is provided with a half round spiral groove 33 which mates with the former groove to provide a spiral channel which contains a plurality of balls 34. The balls 34 are inserted into the channel formed by grooves 32 and 33 through a'tapped opening 35 in sleeve nut 21. The opening 35 is located adjacent the upper end of groove 32 and has a plug 36 screwed therein which acts as a stop to limit upward movement of the balls 34 within said groove. Sleeve nut 21 also has a pin 31 fixed thereto, said pin being located adjacent the lower end of groove 32 to limit downward movement of the balls 34 therein. The screw 29 is provided with stop pins 38 and 39 for limiting movement of the balls 34 in opposite project intothe space between the shank 3| and portion II of sleeve nut 21.

Motor 2' when energized rotates in a clockwise direction as indicated by arrow A (Fig. 1), and as is apparent from Fig. 2 when sleeve nut 21 is rotated in this direction the balls :4 roll within the r grooves 22 and 22 to move screw 22 upwardly out of the position shown in Fig. 2. The pitch of the grooves 22 and 33 is such that the balls 24 are adapted to effect counterclockwise rotation of sleeve nut 21 when motor 26 is deenergized and downward pressure is applied to the screw 29.

Theshank II of screw 22 is slidable within an opening in a guide member 42 mounted upon the upper end of sleeve nut 21 and the upper end of said shank is provided with a slot 43 for receiving the free end of arm H and carries a screw 44 for engaging said arm on the upper side thereof and a pin 45 for engaging said arm on the under side thereof. The guide member 42 is provided with a shouldered portion which fits within thevsleeve nut 21 andthe same is recessed to receive oppositely disposed upwardly extending projections 40-4! on the upper end of said sleeve nut. The projections 4H8 prevent rotation of guide member 42 with respect to sleeve nut 21 and said projections are recessed to receive a washer 41 which engages the upper face of said guide member to hold the same in position upon said sleeve nut. The lower face of guide member 42 is provided with oppositely disposed downwardly extending projections 42-42, and upon upward movement of. screw into a given limit said lugs are engaged by the end portions 4lI-4li of pin 39, as shown in Fig. 6, to stop clockwise rotation of sleeve nut 21 with respect to said screw. The projections 4646 on the upper end of sleeve nut 21 cooperate with a stop 50 which is held within the slot 42 on the upper end of shank 3i by the pin 45. Upon downward movement of screw 29 into a given limit the opposite ends of stop to move into engagement with the projections 4646 as shown in Fig. 4 to limit counterclockwise rotation of the sleeve nut 21 with respect to screw 29.

The lower end of sleeve nut 21 is closed by wall II having a cup projection 52 on the under side thereof. The slip clutch 28 is mounted within the cup projection 52 and includes a driving element 52 slidably mounted upon the shaft of motor and a pair of cooperating friction rings 5454. The driving element 53 is provided with a hub having a square opening therein for receiving a squared portion on the shaft of motor 25 and the same is also provided with a projecting flange 55 which is located between the friction rings 54-54. Friction rings 5454 and flange 55 are clamped together between the lower face of wall SI and a thrust ring 56 by a spring 51 which is held under compression between said thrust ring and a washer 58 secured within a groove provided on the lower end of the cup projection 52., Cup projection 52 is provided with oppositely disposed slots 58-59 and thrust ring 56 has oppositely .disposed lugs 6H0 secured thereto which project into said slots to prevent rotation of said thrust ring within said cup projection. Sleeve nut 21 is supported upon the upper end of the shaft of motor 25 by a ball 02 which engages within recesses provided in the upper end of said shaft and in the lower face ofwall ll.

"As is apparent from the foregoing, upon energisation of motor 25 sleeve nut 21 is driven through the medium of driving element II and friction rings 54 in a direction to move screw 2! and arm I i upwardly against the action of spring II for release of the brake. As hereinbefore set forth,

when screw 20 is moved upwardly into a givenlimit, clockwise rotation of sleeve 21 is stopped by engagement of pin 28 with the projections 42-42 on guide member 42. Upon stopping of clockwise rotation of sleeve nut 21 the motor is stalled but 1 is maintained energized to hold the brake in released position.

such that prior to stalling of the motor driving element! slips with respect to friction rings 84 to thereby frictionally dissipate the kinetic energy present in the moving parts of the motor. Upon deenergization of motor 2! the screw 29 moves downwardly under the action of spring l9 to permit setting of the brake. forth the sleeve nut 21 is then driven in a counterclockwise direction, and upon downward move-- ment of the screw into a given limit counterclockwise rotation of said sleevenut is stopped by engagement of stop 50 with the projections 48-46 on the upper end of a said sleeve nut. During counterclockwise rotation of sleeve nut 21 motor 25 is driven through the medium of slip clutch 22 and upon stopping of counterclockwise rotation of said sleeve nut the kinetic energy present in the moving.parts of the motor is frictionally dissipated by the slippage of the driving element-i! with respect to friction rings 54.

Sleeve nut 21 is partially filled with oil, and in order to prevent the escape of oil through the upper end of said sleeve nut a packing ring 84 is clamped between the lower face of cup member 42 and the shoulder formed by the portion 20 within the sleeve nut 21. operation of the brake screw 29 acts as a piston within the sleeve nut 21 to force oil through the channel formed bygrooves 32 and I3 and around the balls 34 contained therein.

What I claim as new and desire to secure by Letters Patent is: l. The combination with a motor and a device to be operated thereby, of power transmitting mechanism therebetween including a pair of members having mating spiral grooves therein, one of said members being associated with said motor to be driven thereby and the other being non-rotatable and being operatively connected to said device. a plurality of balls located within said grooves for eflecting axial movement of said latter member upon rotation of said fprmer member and a slip clutch driving connectionbetween said motor and said former member.

2. The combination with a torque motor-and a device to be operated thereby, f a power transmitting mechanism therebetween including parts having mating spiral grooves therein, one of said parts being associated with said motor to be driven thereby and the other being non-rotatable .and being operatively connected to said device, a plurality of balls located within said grooves for effecting axial movement of said latter member upon rotation of said former member, means for stopping rotation of said former member in opposite limits, and a slip clutch driving connection between said motor and said former member adapted to slip upon stopping of said former member.-

3. Thecombination with a spring set brake, of an operating motor therefor, a speed reducing As hereinbefore set.

However, the arrangement is As is apparent, upon 1 driving connection between said motor and said brake comprising a screw jack having cooperating rotatable'and non-rotatable screw elements, the latter being movable axially with respect to said former element upon rotation of said former element and being operatively connected to said brake and a slip clutch driving connection between said motor and said former screw element.

4. The combination with a brake having spring 1 means associated therewith for effecting setting thereof, of an operating motor therefor, a speed reducing driving connection between said motor and said brake including a sleeve rotatable by said motor, a non-rotatable member located within said sleeve and operatively connected to said brakefsaid sleeve and said member having mating spiral grooves therein, and a plurality of balls located within said grooves for eflectlng axial movement of said member in a direction to release said brake upon rotation of said sleeve by said motor.

5. The combination with a brake having spring means for effecting setting thereof, of an operating motor therefor, a screw jack operating connection between said brake and said motor, said jack being movable into a given limit upon energizati'on of said motor to effect release of said brake and being returnable to an opposite limit upon deenerg'ization of said motor to permit resetting of said brake and a slip clutch driving connection between said motor and said screw jack for Irictionally dissipating the kinetic energy Dres ent in said motor uponmovement of said screw jack into either of said limits.

HOWARD E. HODGBON. 

